The cyclic nature of the stick-slip phenomenon may cause catastrophic failures in drill-strings or at
the very least could lead to the wear of expensive equipment. Therefore, it is important to study the
drilling parameters which can lead to stick-slip, in order to develop appropriate control methods for
suppression. This paper ...

The cyclic nature of the stick-slip phenomenon may cause catastrophic failures in drill-strings or at
the very least could lead to the wear of expensive equipment. Therefore, it is important to study the
drilling parameters which can lead to stick-slip, in order to develop appropriate control methods for
suppression. This paper studies the stick-slip oscillations encountered in drill-strings from both numerical
and experimental points of view. The numerical part is carried out based on path-following methods for
non-smooth dynamical systems, with a special focus on the multistability in drill-strings. Our analysis
shows that, under a certain parameter window, the multistability can be used to steer the response of
the drill-strings from a sticking equilibrium or stick-slip oscillation to an equilibrium with constant drillbit
rotation. In addition, a small-scale downhole drilling rig was implemented to conduct a parametric
study of the stick-slip phenomenon. The parametric study involves the use of two flexible shafts with
varying mechanical properties to observe the effects that would have on stick-slip during operation. The
experimental results demonstrate that varying some of the mechanical properties of the drill-string could
in fact control the nature of stick-slip oscillations.